P1691

CHECK ENGINE





Fault Symptoms.
CHECK ENGINE lamp (MIL) on continuously or out of order.

Conditions.
P1691
^ Engine speed higher than 80 rpm.
^ Battery voltage 7.5 to 17 V.
^ Open circuit.

P1692
^ Engine speed higher than 80 rpm.
^ Battery voltage 7.5 to 17 V.
^ Shorting to ground.

P1693
^ Engine speed higher than 80 rpm.
^ Battery voltage 7.5 to 17 V.
^ Shorting to battery positive (B+).





Diagnostic Help.
The CHECK ENGINE lamp (MIL) can be activated with the ISAT scan tool.
- Select "ACTIVATE".
- Select "CHECK ENGINE LAMP".
The command activates the lamp at a frequency of 0.5 Hz for 30 seconds.

The status of the CHECK ENGINE lamp (MIL) can be ascertained with the ISAT scan tool.
- Select "EDU".
- Select "READ VALUES".
- Select "CHECK ENGINE LAMP".
The ON or OFF status of the lamp will be shown.

Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the wiring at several points and in different directions to ascertain whether the wiring harness, including any connectors, is causing the trouble. Observe the multimeter, ISAT scan tool or test lamp while doing this.





Diagnostic Procedure.
1. Check the control module output
- Unplug the EDU control module's connector.
- Connect a test lamp to pin 12 of the EDU's connector and battery negative (B-).
- Connect the ISAT Scan Tool.
- Select "ACTIVATE".
- Select "CHECK ENGINE LAMP".

The lap should flash at a frequency of 0.5 Hz for 30 seconds.

Lamp flashing?
YES: Carry out fault diagnosis at EDU programmable trip computer. Then continue with point 2.
NO: Check and if necessary repair or replace the lead between pin 12 of the EDU's connector and pin 8 of the Motronic control module's connector.
Then continue with point 2.





2. Final check
- Clear the diagnostic trouble code.
- Implementation of driving cycle:
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Evaluation of driving cycle:
^ Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?
YES: Continue as described at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO: The steps taken to rectify the fault were correct.